A conventional combination dehydration full-automatic washing machine is configured to include a rotating tub rotatably installed in an outer tub as a combination dehydration tub and washing tub, and further include a pulsator rotatably mounted on the bottom portion of the rotating tub. Since the pulsator and the rotating tub are rotatably driven by a single drive motor, rotation of the drive motor is transferred to the pulsator in a state where the rotating tub is braked and stopped, to thus make the pulsator driven in forward and reverse rotation modes at a relatively low speed, when running a washing operation. Meanwhile, when running a dehydration operation, braking of the rotating tub is released and rotation of the drive motor is transferred to the rotating tub and the pulsator without deceleration, to thereby rotationally drive the rotating tub and the pulsator.
A clutch structure and a reduction gear mechanism are needed along a rotating force (or torque) transmission path from the drive motor to the rotating tub and the pulsator in order to switch the rotating force transmission path. For this reason, the conventional combination dehydration full-automatic washing machine has quite a complex configuration to thus cause poor manufacturability and assembly performance and to resultantly increase manufacturing cost. In addition, a control circuit transmission path switching operation does not work in progress due to the poor manufacturing accuracy and deterioration over time of the clutch mechanism to thereby cause unstable switching reliability in some cases.
Moreover, during performing a switching operation from a washing operation to a dehydration operation, there is a noise problem caused by a switching operation sound of the clutch mechanism or an operation sound generated from the reduction mechanism. In addition, there is a problem that a long laundry time is taken due to a prolonged switching operation of the clutch mechanism.
Theconventional full-automatic washing machine has been proposed in Korean Patent Application Publication No. 10-2003-0077682 (hereinafter, referred to as Patent Document 1), and includes: a dehydration tub that is rotatably mounted in an outer tub; a pulsator that is installed in the dehydration tub, and is independently rotatable from the dehydration tub; a dehydration shaft that is supported rotatably in a shaft support bearing case, and transmits the rotational power to the dehydration tub; a washing shaft that transmits the rotational power to the pulsator; a BLDC (BrushLess Direct-Current) motor in which a rotor rotates as current is supplied for a stator; and a switchable clutch mechanism that can switch a power transmission path of a motor to the washing shaft or the dehydration shaft in correspondence to a washing stroke or dehydrating stroke.
Patent Document 1 has disclosed a control method of the full-automatic washing machine, in which an operation of switching the BLDC motor to the left and right directions is performed in order to cancel locking of a coupling prior to a step of raising the coupling up to a washing mode position by turning on a clutch motor after completion of supplying water for washing, and serration of the inner circumferential surface of the coupling receives a surface pressure acting in the opposite direction to each other from serration of a lower end of the dehydration shaft and serration of an upper end of an inner connector by a mismatch of the dehydration shaft and the inner connector that are coupled to the coupling, to thus prevent a phenomenon of constraining an ascending of the coupling upon drive of the clutch motor.
The above-described conventional full-automatic washing machine is provided with a clutch motor to ensure that power is selectively transmitted to the washing shaft and the dehydration shaft, to accordingly cause a problem that the dehydration tub and pulsator cannot be driven independently and thus a variety of water flows cannot be formed.
In addition, in Patent Document 1, since the washing stroke of low-speed and high-torque characteristics and the dehydration stroke of high-speed and low-torque characteristics should be performed by using a single drive motor, a motor design cannot be optimized for any one stroke of the washing machine. As a result, a high-speed rotation problem that can be caused during the dehydration stroke can be solved by designing a motor somewhat optimized for the washing stroke and conducting a so-called field-weakening control during the dehydration stroke, but there is a problem accompanying a complex control.
In order to solve the problems of Patent Document 1 requiring the high-torque in the washing stroke and the field-weakening control in the dehydration stroke, Korean Patent Registration No. 10-0548310 (hereinafter, referred to as Patent Document 2) including a planetary gear set and a clutch mechanism has been proposed.
The conventional washing machine disclosed in Patent Document 2 includes: an outer case forming an outer shape; an outer tub which is supported on an inside of the outer case for receiving wash water therein; an inner tub which is rotatably accommodated in an inside of the outer tub and is used for both washing and dehydrating; a pulsator which is mounted in an inside of the inner tub relatively rotatably, to form a washing water flow; a drive motor for generating a driving force for rotating the inner tub and the pulsator; an inner tub rotating shaft which receives the driving force of the drive motor for rotating the inner tub; a pulsator rotating shaft which receives the driving force of the drive motor for rotating the pulsator; a sun gear which is connected to the drive motor and is connected to the pulsator rotating shaft; a plurality of planetary gears which are simultaneously engaged with the sun gear and a ring gear; a carrier supporting the planetary gears so as to be rotated and revolved; and a clutch spring for controlling the rotation of the inner tub and the pulsator during washing or dehydrating.
The conventional washing machine of Patent Document 2 has a planetary gear set including the sun gear, the ring gear, the planetary gears and the carrier, and reduces the rotating force of the drive motor, to then be transferred to the pulsator and the inner tub, and operates a clutch spring to selectively transmit power to the pulsator and the inner tub, to thus rotate only the pulsator during washing and both the pulsator and the inner tub simultaneously during dehydrating.
However, the conventional washing machine having the planetary gear set as in Patent Document 2 has a structure of rotating the pulsator and the inner tub only in an identical direction since the planetary gear set is supported by a one-way bearing, and thus cannot rotate the pulsator and the inner tub in directions opposed to each other. In addition, the conventional washing machine having the planetary gear set as in Patent Document 2 employs a single drive motor and causes a problem of failing dual power implementation.
In order to solve the above-described defects of Patent Document 2, a dehydration combined washing machine disclosed in Korean Patent Application Publication No. 10-1999-0076570 (hereinafter, referred to as Patent Document 3) includes: an outer box; an outer tub that is resiliently supported via a plurality of elastic hanging mechanism in the outer box; a rotating tub serving as a washing tub and a dehydration tub that are rotatably disposed within the outer tub; a pulsator that is installed in the rotating tub; a washing motor that is installed to directly drive the pulsator and that is controlled at a variable speed; and a dehydrating motor that is installed to directly drive the rotating tub and that is controlled at a variable speed, wherein a rotor of the washing motor is rotatably attached to the pulsator at a lower end of a rotation shaft of the pulsator, and a rotor of the dehydrating motor is rotatably attached to and integrated with the rotating tub at a lower end of a rotation shaft of the rotating tub.
In the washing machine of Patent Document 3, the washing motor is constructed into an outer rotor type with a larger diameter than that of the dehydrating motor, and the dehydrating motor is composed of an inner rotor type, in a manner that the washing motor has low-speed and high-torque motor characteristics, and the dehydrating motor has higher-speed and lower-torque motor characteristics than those of the washing motor, to thereby have a positional relationship between the washing motor and the dehydrating motor where the washing motor is located at an outer side and the dehydrating motor is located at an inner side.
In the washing machine of Patent Document 3, the washing motor is constructed into the outer rotor type with a larger diameter than that of the dehydrating motor, but has a problem of having an insufficient drive torque to handle a large capacity laundry in a large-capacity washing machine.
In addition, in the washing machine of Patent Document 3, only the washing motor is made to rotate in a forward or reverse direction at a predetermined rotating speed, or the washing motor is made to rotate in a forward direction and the dehydrating motor is made to rotate in a reverse direction, at a state where the rotating tub is sopped by DC exciting the dehydrating motor during a washing stroke to then be set to be in a braking mode, and accordingly the rotating tub is in a substantially stationary state without rotating in an opposite direction by and against a load such as a quantity of laundry and an amount of water to thus achieve to prevent idling.
Moreover, the washing machine of Patent Document 3 has proposed a structure of using two drive motors although a start-up torque of the rotating tub makes a greater action than that of the pulsator in consideration of the heavyweight rotating tub and a load such as a large capacity of a quantity of laundry and an amount of water, wherein the pulsator is driven by the washing motor that is constructed into an outer rotor type with a larger diameter than that of the dehydrating motor and is located at an outer-more side than the dehydrating motor, to have low-speed and high-torque motor characteristics. As a result, the washing machine of Patent Document 3 drives the pulsator and the rotating tub in mutual reverse directions to thus cause a problem of failing to implement a strong flow of water for washing.
Thus, the washing machine of Patent Document 3 has disclosed a structure of independently driving the pulsator and the rotating tub by using two drive motors, but does not propose a variety of types of flows of water for washing using the same.